Electronic burn-in system

ABSTRACT

A system for performing electronic burn-in testing of a component comprising a rack (20) which is electrically connectable to a power source. A tray (50) is on the rack and a mother board (MB) associated with the tray is electrically connectable to the rack. A daughter board (DB) is electrically connectable to the mother board and to a component to be tested. The daughter board is electrically dedicated to the component but neither the tray nor the mother board are dedicated to the component.

This application is a division of application Ser. No. 336,781, filedJan. 4, 1982, now U.S. Pat. No. 4,542,341.

TECHNICAL FIELD

This invention relates to test equipment and, more particularly, toequipment for testing electronic components prior to their actualusuage.

BACKGROUND OF THE INVENTION

It is common practice to test electronic components prior to theiractually being installed. In the process, components are subjected toextreme conditions, greater than those they will experience in actualusage to weed out weak or defective parts. For example, it is notuncommon to test a component for hours, if not days, under temperatureconditions approaching 85° C. Such testing is referred to as burning-in.There are a number of burn-in systems in use today. However, they tendto be very expensive because they are generally custom designed anddedicated only to a particular component or circuit to be tested.Applicants have been making customized burn-in racks for the electronicsindustry for some time which are designed specifically and wiredprecisely in accordance with the tests planned for the units to betested, A system designed and hand wired to a specific component orcircuit is known as a "dedicated" system.

Racks containing the units to be tested, are placed in temperaturecontrolled chambers. The racks are wired into electronic test equipmentwhich is usually outside the chamber in a separate control room. Thecontrol room contains a power source and various types of analyticalequipment. In the prior art racks, the units under test are inserteddirectly into each rack. Thousands of wires connect the units under testto the power source.

Generally, after a period of time (a year or so), the user changes thespecific product being tested because a new product has come along andreplaced the earlier one, or the specific product has been modified. Theonly way to insert and test such a new product is to completely redesignor modify the rack wiring. This involves desoldering and completerefrabrication, often times costing in the hundreds of thousands ofdollars in labor.

An object of the present invention is to provide a rack which iscompletely reusable requiring no desoldering and which is completelynondedicated to any particular unit to be tested.

It is also an object that the racks be completely adaptable to any unitto be tested and wherein two or more different units can simultaneouslybe tested without altering the wiring connecting the rack to the testequipment.

DISCLOSURE OF THE INVENTION

In accordance with the above objects, applicants have provided a systemfor performing electronic burn-in testing of a component comprising arack which is electrically connectable to a power source. There is atray on the rack and a mother board is associated with the tray andelectrically connectable to the rack. A daughter board is electricallyconnectable to the mother board and to a component to be tested. Thedaughter board is electrically dedicated to the component and neitherthe tray nor the mother board are dedicated to the component. In oneembodiment of the invention, racks are provided which accept twelvetrays. Each tray in turn has ten positions, each of which accepts oneunit to be tested, which unit is wired to a daughter board. It istheoretically possible therefore that 120 different units can undergosimultaneous testing.

In accordance with another feature of the invention, the trays areadjustable in size to accomodate daughter boards of varying sizes andshapes and the racks in turn are adjustable to accomodate trays ofvarying sizes.

DESCRIPTION OF THE DRAWINGS

These, and other features of the invention including various noveldetails of construction in combinations of parts, will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims. It will be understood that the particularburn-in system embodying the invention are shown by way of illustrationonly and not as a limitation of the invention. The principals andfeatures of this invention may be employed in varied and numerousembodiments without departing from the scope of the invention.

In the drawings:

FIG. 1 is a schematic plan view of two contiguous factory test roomscontaining electronic test equipment in one and a burn-in systemembodying the present invention in the other.

FIG. 2 is a semi-schematic wiring diagram showing the relationshipbetween the mother board, the daughter board and the units under test inside elevation.

FIG. 3 a perspective view of the present invention embodying a burn-inrack including a tray containing a mother board and daughter boards.

FIG. 4 is a side elevation of a burn-in rack containing one tray.

FIG. 5 is a front elevation of a burn-in rack containing one tray.

FIGS. 6 and 7 are a plan view and a side elevation respectively of atray.

FIG. 8 is a plan view of a mother board.

FIG. 9 is a detailed view in front elevation of a power interfaceassembly plate for connecting a test rack to the electronic testequipment.

FIGS. 10 and 11 are views of a tray just prior to and after having beeninserted in the rack respectively.

FIG. 12 a detailed view in rear elevation of a daughter board carrying aunit under test just prior to being inserted in a tray.

FIG. 13 is a rear elevational view of the end of a tray and add-onplates increase the size of the tray to accomodate a larger sizedaughter board.

FIG. 14 is a front elevational detail view of the rack and tray in theposition seen in FIG. 11.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, there will be seen schematically a plan view of twocontiguous hypothetical test rooms in an electronics plant. Room 2 onthe right houses electronic test equipment 4 including computing andanalyzing equipment. A conduit 6 enters from adjacent room 8 which is awalk-in, burn-in chamber where a plurality of racks 10 are located.Heating means 12 is provided to raise the temperature of the burn-inroom including the racks and the units under test, herein also (UUT), totemperatures as high as 85° C. After placing the racks in the burn-inchamber and after they have been loaded with trays containing daughterboards with the UUTs on them, the operator leaves the room thereafter toreturn only after the test is completed. He switches on the heatingmeans, if such is required in the specific test, turns on the electricaltest equipment and thereafter monitors the test results as required.

Referring to FIGS. 3, 4 and 5, there will be seen a perspective view ofa rack 20 containing one tray 50 and a plurality of daughter boards DB.The rack 20 is constructed of tubular aluminum and includes a base 22.Upstanding from the base 22 are front and rear vertical supports 24, 26respectively. Each support is made up of a pair of tubular frame members28 that are joined by braces 30. Extending laterally from the members 28are arms 32 supporting guideways 34 made of L and T-shaped aluminumstock.

On the front of the rack, extending outwardly from the supports 24 arefront panel frames 36, 38. The arms 32 which mount the guideways 34 areadjustable height-wise with regard to the frame means in prebored holes40 in the members 28 to accomodate trays of varying heights.

Referring next to FIGS. 6 and 7 a tray will now be described. Each tray50 comprises four horizontally extending frame members 52. Extendingacross the upper frame members 52 are guideways 54 each grooved as at 59to accept the upper edge of a daughter board DB which mounts a separateunit under test UUT, better seen in FIG. 11.

Constituting a portion of the bottom of the tray as viewed in FIG. 7 isthe mother board MB which mounts a plurality of zero insertion forceconnector members (hereinafter ZIF) connectors. The mother board will bedescribed in greater detail hereinafter. Suffice it to say that the ZIFconnectors are in vertical alignment with the guideways 54 to acceptslidably a daughter board DB as shown in FIGS. 10 and 11. The ends oftray 20 are provided with end plates 56. Nylon glides 57 (seen also inFIG. 12) underlie the lower guide rails 52.

As seen in FIG. 13 and in dotted outline in FIG. 12 the trays 20 may beincreased in height by the addition of spacer plates 60 or 62 which maybe secured by threaded connections 64 to the top of the trays, thepurpose being to accomodate daughter boards of greater size. Accordinglythe rails 34 on the rack 10 would be repositioned in the holes 40 on therack to accomodate the higher trays. The upper rails 52 would then berepositioned on top of the extender 60, 62.

The mother board will now be described, particularly with reference toFIGS. 2 and 8. They constitute the bottoms of the trays 50 and comprisea pair of printed circuit boards having 36 pairs of conductive paths 62aand 62b in alignment on their upper and lower surfaces. Because themother boards are made in two pieces, the conductive paths are joined byhard wiring as at 64. The conductive paths terminate in connectors 66 atthe ends of the board between notches 68 and 70. The notch 70 being ofgreater depth than notch 68, makes the boards asymetrical and preventsthe boards and hence the trays from being inserted in the racks with thewrong end forward. Ten ZIF connectors, only two of which are seen inFIG. 8, are spaced across the mother boards and soldered to the 36 pairsof conductive paths.

Referring next to FIG. 9, there will be seen a power interface assemblyplate 80 which connects the rack to the source of power. There is oneinterface plate for each tray on the rack. They are located verticallyat the closed end or the end nearest the viewer as seen in FIG. 3. Eachinterface plate 80 comprises a mounting panel 82 and 36 hard wireterminals 84 arranged 18 in each of two rows one above the other atright angles on the face of the panel 82. A horizontally extending ZIFconnector, ZIF-86 (see FIGS. 10 and 11) extends through the panel 82.Each terminal 84 is hard wired to a contact 88 by means of a wire 90.Any plurality of interface terminals 84 may be bussed together as shownat 100. The interface terminal of each assembly plate 80, there being 12on the rack shown in FIG. 3, are hard wired to the users electroniccontrol equipment 4 by conduit 6 as seen in FIG. 1.

Each ZIF connector is a commercially available component having ahousing 104 (FIG. 8) and 36 pairs of contacts 106, each pair of contactsbeing electrically soldered in parallel relationship to one of the 36conductors 62. A tripping lever 108 is located at the end of each ZIFconnector to open and close the contacts.

Automatic means for opening and closing the connector ZIF-86 is providedon the forward end of each tray. With reference to FIG. 10, ZIF-86 islocated at the lower portion of the mounting panel 82 of the interfaceplate 80 with its operating lever 108 inclined at about 30° to thehorizontal. An aligning pin 110 projects rearwardly from the panel 82.An aperture 112 in the face plate 56 of the tray 50 is aligned with thepin 110. An elongate aperture 114 along the bottom of the faceplate 56permits the plate to clear the lever 108 as the tray is moved from rightto left as viewed in FIG. 10 at which time the aligning pin 110 entersthe hole 112 to cam the tray into correct alignment with the then openZIF-86.

A cam 115 on the leading end of the tray engages the lever 108 moving itupwardly in a counterclockwise direction thereby closing the contacts ofZIF-86 into engagement with the contacts 66 on the mother board to makeelectrical contact as shown in FIG. 11.

Upon removing the tray from the rack after the test has been completed,when the tray is pulled out or to the right as viewed in FIG. 11, theback of the plate 56 , against which the lever 108 has been resting,pulls the lever downwardly in a clockwise direction to open the contactsof ZIF-86.

Signal lights 120, 122 are mounted on the upper left hand edge of eachdaughter board (see FIG. 12), both being light emitting diodes, theupper LED 120 is red and is wired to the daughter board to indicate thatthere is power coming from the power source in the electronic testequipment. The lower light 122 is green and when glowing indicates thereis a voltage coming from either the unit under test or the daughterboard per se.

The daughter boards may be wired with self generating voltage sourceswhere for example the voltage to be applied to one of the elements ofthe units under test is not a standard voltage or one coming from theelectronic test equipment source through one of the 36 leads.

Next referring to FIG. 2, there will be seen a modified semi-schematicshowing of the circuitry of the burn-in system. Conduit 6 which is aharness of many separate wires, brings voltage to the test racks. One ofthe separate leads in the conduit 6 is designated 6a and brings a sourceof test voltage to one of the terminals 84 on the interface assemblyplate 80. For illustrative purposes, it will be assumed that lead 6abrings in 10 amps at 5 volts which is one of the test voltages which maybe selected by the daughter board.

The current path is split, passing along parallel wires 90a and 90b tothe connector ZIF 86 on the back of the interface panel 80. The currentpath continues, passing to the upper and lower contacts 66a and 66b inthe mother board thence through conduits 62a and 62b, through thecontacts 105, 106 to the contacts 132a and b on the daughter board. Tothis point none of the current carrying parts, i.,e., the rack, tray ormother board, are dedicated to anything. Five amps of current at 5 voltsmove along each of the lines 62 and thence to the daughter board whichis dedicated by being designed in accordance with the unit under test(UUT). Ten amps at 5 volts is thus delivered to UUT.

Referring to FIG. 12, the daughter board DB is specifically dedicated tothe particular unit or component of the unit under test. The componentor components are mounted on the daughter board and electricallyconnected by printed circuit to one of the contacts 132 on the loweredge of the board. When the daughter board is fully inserted into one ofthe ZIF connectors on the mother board, contact is made with theappropriate contacts 105, 106 in the ZIF connector to select the desiredtest voltage, in this instance 10 amps at 5 volts. The current returnsalong another line out of the daughter board DB into the mother boardand thence back through the power interface assembly 80 to the source inthe electronic test equipment unit.

It will be noted that there are 36 leads, 18 of which can supply 10 ampsof current to any particular component of a unit under test while 18return the current to the source. It is possible however to test morethan 18 components at a given time. For example, 24 lines may feed 24separate components with the remaining 12 lines serving as returnconduits when appropriately bussed together.

Thus with the above described non-dedicated rack and tray, unlike ordifferent components may simultaneously be tested.

We claim:
 1. A system for performing electronic burn-in testing of twoor more modules comprising a rack, a removable tray on the rack, aremovable daughter board receivable in the tray, and a source of aplurality of specific test voltages of predetermined amounts,the rackhaving support means for receiving and releasable supporting at leastone removable tray, at least one power interface assembly on the rackfor connecting the rack to the source of the plurality of test voltages,a plurality of releaseable electric connectors on the interface assemblyfor connection to the removable tray, the tray having a mother boardincluding a plurality of conductive paths for conducting one of thespecific voltages in each path, each path being connected to a contactthat is engageable with one of the releasable connectors on theinterface assembly, means on the mother board circuit for receiving andreleasably supporting a removable daughter board, a plurality ofreleaseable connectors on the mother board each connected to aconductive path to support a plurality of specific voltages to thedaughter board, the daughter board having a plurality of contacts eachengageable with one of the releaseable electric contacts on the motherboard, the daughter board having means for mounting two or moredifferent modules, each module being connected to a conductive path toone or more contacts on the daughter board to receive the specific testvoltages in the conductive path in the mother board to which thecontacts on the daughter board are connected, signal means on thedaughter board to indicate the presence of test voltage across themodule, signal means on the daughter board to indicate the presence ofvoltage generated from the module or the daughter board, and means toelectrically connect and disconnect the rack and the tray automaticallyupon the tray being moved into and out of the rack.